Drill-bit



-'P. G. MIDGETT.

DRILL BIT.

APPLICATION FILED SEPT. 2, I9I9.

1 344,425 Patented June 22, 1920.

5 vwamtoz PENELTON e. MIDGETT, or DALLAS, TnXAs, AssIGNoR or ONE-HALF T0 nossnn TH01VLAS,0F n LLAsm xAsw V V I DRIL -BIT.

Specification of Letters Patent. Patented J n 2 2 192() Application filed September 2,. 1919. Serial No. 320,971.

To all whom it may concern .7

'Be it known that I, PENELTON G.M1Dcnrr,

a citizen of the United States, residing at Dallas, in the county of Dallas and State of Texas, have invented certain new and useful ,Improvementsin Drill-Bits, of which the o-nected thereto. The point is of the usual twist drill formation except that the cut-.

following is a specification.

I This invention relates to new and useful improvements in drill bit constructions.

The invention has particularly to do with drill bits such as are used in drilling wells, and the aim of theinvention is to produce a bit which will be superior in many respects.

One of the particular features resides in a joint between the bit point and head whereby the point may be readily removed and others substituted; said joint involving liberal. contacting surfaces between the point and the head, and a locking arrangement whereby the parts are adequately secured together and ample contact therebetween in the direction of rotation, is had. Another salient point of the invention resides in the provision of a lug and socket therefor which form part of the aforesaid joint and afford a positive connection between the head and the bit so that independent circumferential movement is precluded and rotation is trans-- mitted to the point without lost motion.

A further feature resides in the disposition of cutting edges at a greater radial distance from the center than the. remainder of the structure whereby ample clearance is given the bit.

The invention will be more readily-understood from a reading of the following specification and by reference to the accompanying drawings, in which an example of the invention is shown, and wherein:

Figure 1 is an elevation of a drill bit structure embodying the invention,

Fig. 2 is a reverse elevation of shown in the Fig. '1,

Fig. 3 is an underside view of the structure,

Fig. 41 is a plan view of the same,

Fig. 5 is an elevation of the bit point at right angles to Fig. 1.

Fig. 6 is an elevation of the head corresponding in position to Fig. 5, n

Fig. 7 is a cross-sectional detail on'ti-aline 7-7 of Fig. 1,

the parts liig. Sis a sectional detail on the line 8 8 of Fig. 1', and I F ig. 9 is an end elevation of the head shown'inFig. 6.

In the drawings the numeral 10 designates a drill bit pointand 11 a head conting edges 12 have the greatest radial protion of Fig. 3. The surface of the point is gradually cut back so as to reduce the diameter of the point toward the trailing edge 13. This construction'gives the point liberal clearance, and a free cutting edge which will operate at its highest efficiency at all times. The point is shouldered at 14: and provided with a shank 15 of reduced diameter. It is obvious thatthe diameter or size of the bit may vary so long as it is greater than that 'of the shank which remains the same for all excessive sizes. 1

The purpose of making the point 10 and the head 11 separate is that an extremely hard and durable steel may be used for the point while the softer and less expensive metal may be utilized for the shank. The point is provided with an angular socket 16 extending radially in its upper end and also is provided with a boss 17 a shoulder 18 eX- tending along one side of the socket and across the base of the boss; and also with a vertical contact face 19.

The head 11 is provided with a depending lug 2O angular in cross-section to snugly fit in the socket 1 6. The head is'recessed at 21 and provided with an upright contact face 22 positioned to engage the boss 17 as is shown in Figs. 11 and 7. The head also 20 and its face 22 impart rotation to the point, the contacting faces'and surfaces in theline of rotation apparent.

The connecting bolt has its head countersunk in a recess 26 inthe boss 17 and its screw-threaded end is engaged in the head being very liberal as is 15. The bolt has a ciromnferential groove 27 near its head. A lag bolt 28 is passed through the boss 17 at right angles to the bolt so as to engage in [the groove 27 and lock said bolt in place. This lag bolt has its screw-threaded end engagedi'n "the head 11. Gn'the opposite side a lag llpolt 29 is passed through the shank l5 anduhas its screw-threaded end engaged in thehead 11. It Will be seen that all of the bolts have their screw-threaded ends engaging in the head which is of the softer metal and may 'be readily threaded, and this precludes the making of screw-threads inthe hard metal of thepoi-nt. The'bolts fasten the polnt and head together and by"i"emovi ng the same the head andbitinaybe easily sepa- The usual Water duets 30 are provided -1n the head for supplying Water to In a drilling bit structure, abit -point 1 and having their side Walls parallel, said bosses fitting in the recesses and disposed in end to end relation With their inner ends contacting, theboss-of the bit-point having a smooth opening and the boss of the head having a screw-threaded opening which are {adapted to be in 'alinem'ent, an "angular 111g *earriedbythe *l'ree end ofthe bossmt' the head "and adapted 'ilfor insertion within "the angularsoeket, and Ba sorewi'passing through "the smooth opening and engaging in the screw-threaded opening. a

In testimony whereof I aflix mysignature.

PENELTON G. 'MIDGETT. 

